The Australian Security Intelligence Organisation (ASIO) is Australia's national security service.

ASIO's main role is to gather information and produce intelligence that will enable it to warn the government about activities or situations that might endanger Australia's national security. The ASIO Act defines "security" as the protection of Australia and its people from espionage, sabotage, politically motivated violence, the promotion of communal violence, attacks on Australia's defence system, and acts of foreign interference.

ASIO's T4 Directorate provides integrated protective security advice to Australian government departments and agencies. With the approval of the Attorney-General, T4 may be able to provide these services to some elements of the private sector. T4 typically provides protective security risk reviews and advice, specialised protective security training and testing and endorsement of security equipment and consultants.